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<head>
    <meta charset="UTF-8">
    <meta name="viewport"
        content="width=device-width, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0, user-scalable=0">
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    <title>Document</title>
</head>
<script>
    // var apple1 = '青苹果',
    //     apple2 = '红苹果',
    //     temp;
    // temp = apple1;
    // apple1 = apple2;
    // apple2 = temp;
    // console.log(apple1, apple2);
    var a = 1,
        b = 2,
        c = 3,
        d = 4;
    // a = a ^ b ^ c ^ d;
    // b = a ^ b ^ c ^ d;
    // c = a ^ b ^ c ^ d;
    // d = a ^ b ^ c ^ d;
    // a = a ^ b ^ c ^ d;
    // console.log(a, b, c, d);
    // console.log(0XF);
    console.log(
        `a    b   cd
    
        ${a + '' + b}
    er asd
    asd`);
    console.log(0 <'1' );
    console.log(isNaN(true));
</script>

<body>

</body>

</html>